(1) Field of the Invention
The present invention relates generally to wire guided weapons testing, and more particularly to a method for recording, displaying and certifying fire control tones being sent to a weapon over a guide wire.
(2) Description of the Prior Art
In order to certify that proper fire control tones are being sent to a wire guided weapon during an actual launch, test launches are conducted in which the weapon is launched and fire control command tones are sent to the launched weapon. The wire guidance command tones are recorded on a strip chart, which must be manually analyzed using a calibrated time-scale to establish tone duration. The tone frequency can be obtained by physically counting the peaks over a time frame. In order for the peaks to be distinguished, the strip chart recorder must be run at maximum speed, creating extremely long recordings for each test firing. The manual interpretation of the strip chart is time consuming and prone to error and is very dependent on the experience level of the personnel performing the measurements.
Accordingly, it is an object of the present invention to provide a method to obtain command tone signals for a wire guided weapon during a test launch.
Another object of the present invention is to provide a method to analyze the command tone signals, which does not rely on manual interpretation of the collected data.
A further object of the present invention is to provide a method to certify that the frequency and duration of the command tone signals are within proper operating parameters.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a method is provided to obtain and process wire guidance fire control command tones. The method is implemented on a computer, which is used in lieu of the strip chart recorder to capture the command tones. When initiated, the method begins data monitoring and displays the data in real time, showing the tone, or signal over time. The real time display is typically updated once per second, or at some other predetermined time period. A user controls the beginning and ending of the capture period by pressing a RECORD/STOP RECORD button. The button may be either a visual display that activates data recording when xe2x80x9cpressedxe2x80x9d by a user mouse click on the display, or may be an electromechanical switch connected with the computer. The captured data is stored within the computer. The file structure of the stored data may include the hull number of the vessel conducting the test, the tube number from which the weapon is fired, the test event, the run number within the event and an identification of the weapon being fired. When the user presses the RECORD/STOP RECORD button once again, no further data is captured and the full record of the captured data is displayed. The display includes active cursors denoting the start and stop of the event. The user may position the cursors independently along the data display so as to bracket a tone event of interest. Once the cursors are positioned, the display is updated to show only the bracketed event along with an indication of the time duration of the event. In addition, the display also shows the signal frequency within the bracketed event. The method may use any one of several well known fast Fourier transform algorithms operating on the data between the cursor locations to calculate the frequency. The user may then continue refining the positions of the cursors to accurately identify the event of interest. Once the event has been satisfactorily identified, the duration and frequency may be compared to specified parameters to certify or reject the wire guided fire control command tone signaling system.
Thus, the method of the present invention provides a computerized method of obtaining and analyzing command tone signals for a wire guided weapon during a test launch. Manual interpretation of the data includes only locating a tone event of interest and positioning a set of cursors about the event. The method automatically calculates the tone duration and frequency based on the cursor positions. The cursor positioning may be further refined to more accurately analyze the event and to certify or reject the system based on the analysis.